docs: def _parse_bold(self):
          """Parse wiki-style bold."""
          reset = self._head
          try:
              stack = self._parse(contexts.STYLE_BOLD)
          except BadRoute:
              self._head = reset
              if self._context & contexts.STYLE_SECOND_PASS:
                  self._emit_text("'")
                  return True
              elif self._context & contexts.STYLE_ITALICS:
                  self._context |= contexts.STYLE_PASS_AGAIN
                  self._emit_text("'''")
              else:
                  self._emit_text("'")
                  self._parse_italics()
          else:
              self._emit_style_tag("b", "'''", stack)